The present invention relates to a tire condition monitoring apparatus, and more particularly to a wireless communication type tire condition monitoring apparatus that enables a driver to monitor the air pressure of a vehicle tire from the passenger compartment.
Japanese Laid-Open Patent Publication No. 2001-56263 describes a wireless communication type tire condition monitoring apparatus for monitoring the condition of a plurality of vehicle tires from the passenger compartment. The monitoring apparatus includes a transmitter arranged in each tire of an automobile to transmit a signal indicating the air pressure of the tire, a receiver for receiving the signal, and a display for informing the driver of the automobile of the air pressure condition of each tire. The receiver includes a plurality of receiving antennas and a synthesizer for outputting a maximum one of the voltages induced in the antennas. When the induction voltage of each receiving antenna is less than the minimum detectable voltage of the receiver, a synthesizer for complementing the induction voltage with another induction voltage that is greater than the sensitivity voltage is necessary. As a result, the tire condition monitoring apparatus of Japanese Laid-Open Patent Publication No. 2001-56263 has a complicated structure.